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105 lines
2.7 KiB
105 lines
2.7 KiB
#!/usr/bin/python
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# -*- coding: utf-8 -*-
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import collections
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import logging
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import heapq
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import time
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class LRUCache(collections.MutableMapping):
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"""This class is not thread safe"""
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def __init__(self, timeout=60, close_callback=None, *args, **kwargs):
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self.timeout = timeout
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self.close_callback = close_callback
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self._store = {}
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self._time_to_keys = collections.defaultdict(list)
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self._keys_to_last_time = {}
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self._last_visits = []
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self.update(dict(*args, **kwargs)) # use the free update to set keys
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def __getitem__(self, key):
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# O(logm)
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t = time.time()
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self._keys_to_last_time[key] = t
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self._time_to_keys[t].append(key)
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heapq.heappush(self._last_visits, t)
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return self._store[key]
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def __setitem__(self, key, value):
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# O(logm)
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t = time.time()
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self._keys_to_last_time[key] = t
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self._store[key] = value
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self._time_to_keys[t].append(key)
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heapq.heappush(self._last_visits, t)
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def __delitem__(self, key):
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# O(1)
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del self._store[key]
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del self._keys_to_last_time[key]
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def __iter__(self):
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return iter(self._store)
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def __len__(self):
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return len(self._store)
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def sweep(self):
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# O(m)
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now = time.time()
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c = 0
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while len(self._last_visits) > 0:
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least = self._last_visits[0]
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if now - least <= self.timeout:
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break
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if self.close_callback is not None:
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for key in self._time_to_keys[least]:
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if self._store.__contains__(key):
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if now - self._keys_to_last_time[key] > self.timeout:
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value = self._store[key]
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self.close_callback(value)
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for key in self._time_to_keys[least]:
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heapq.heappop(self._last_visits)
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if self._store.__contains__(key):
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if now - self._keys_to_last_time[key] > self.timeout:
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del self._store[key]
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c += 1
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del self._time_to_keys[least]
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if c:
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logging.debug('%d keys swept' % c)
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def test():
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c = LRUCache(timeout=0.3)
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c['a'] = 1
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assert c['a'] == 1
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time.sleep(0.5)
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c.sweep()
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assert 'a' not in c
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c['a'] = 2
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c['b'] = 3
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time.sleep(0.2)
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c.sweep()
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assert c['a'] == 2
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assert c['b'] == 3
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time.sleep(0.2)
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c.sweep()
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c['b']
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time.sleep(0.2)
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c.sweep()
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assert 'a' not in c
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assert c['b'] == 3
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time.sleep(0.5)
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c.sweep()
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assert 'a' not in c
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assert 'b' not in c
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if __name__ == '__main__':
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test()
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